Run results for: undefined vs. typeof vs. in vs. hasOwnProperty

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:56.0) Gecko/20100101 Firefox/56.0

Browser: Firefox 56

Operating system: Windows

Device Platform: Other

Date tested: 6 years ago

Script Preparation code:

var obj = { a: 1, b: 2, c: 3, d: 4, e: 5 };

obj.check = function(name) { return !!this[name]; };

Tests: